Silver nanoparticles formed in bio- and chemical syntheses with biosurfactant as the stabilizing agent |
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Authors: | Barbara Mendrek Joanna Chojniak Marcin Libera Barbara Trzebicka Przemysław Bernat Katarzyna Paraszkiewicz |
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Institution: | 1. Centre of Polymer and Carbon Materials, Polish Academy of Sciences, Zabrze, Polandbmendrek@cmpw-pan.edu.pl;3. Department of Environmental Microbiology, Institute for Ecology of Industrial Areas, Katowice, Poland;4. Centre of Polymer and Carbon Materials, Polish Academy of Sciences, Zabrze, Poland;5. Department of Industrial Microbiology and Biotechnology, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland |
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Abstract: | In this work, the comparison of the physical properties of silver nanoparticles (AgNPs) obtained via the reduction of silver nitrate (AgNO3) in biological and chemical (model) syntheses supplemented with the biosurfactant surfactin is described. In the studies, two strains of Bacillus subtilis (denoted T’1 and I’1a) were used. The biological synthesis of AgNPs was performed using supernatants obtained from cultures of bacteria growing on brewery effluents, molasses, and Luria–Bretani (LB) medium. In model experiments, ascorbic acid served as the reductant; surfactin acted as the stabilizing agent. The surfactin concentrations were adjusted to 5 and 30?mg/L, which corresponded to minimum and maximum surfactin concentrations as measured in the supernatants obtained from the B. subtilis cultures. The chemical synthesis was carried out at acidic as well as alkaline pH. Dynamic light scattering (DLS) revealed that in model and biological samples, single AgNPs were accompanied by aggregated structures. Transmission electron microscopy showed that the contribution of the aggregates in bacterial supernatants and in chemical synthesis is negligible under acidic conditions. However, in the alkaline environment, this contribution predominates. In the model experiments, smaller nanoparticles were formed with higher concentrations of surfactant. The presence of surfactin significantly increased the stability of AgNPs in both bio- and chemical syntheses. |
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Keywords: | Bacillus subtilis biosurfactant dispersions silver nanoparticles surfactin |
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